In a conventional fuel injector the magnetic cup with coil brace and magnetic coil wound thereon is slipped over the sleeve-shaped housing section and placed on a lower housing part via its cup opening, the lower housing part fixing a valve-seat support in place on the sleeve-shaped housing section. Via the inner cylinder wall of its support body, the coil brace sits directly on the sleeve-shaped housing section and is surrounded by the cup wall of the magnetic cup with air clearance. The magnetic cup has a cup nipple, which extends axially along the cup base, is integrally formed with the cup base and encloses the sleeve-shaped housing part. Using machining, a circumferential labyrinth is cut into the outside of the cup nipple. A second labyrinth is introduced on the sleeve-shaped housing part by machining, with axial clearance from the cup nipple. The sleeve-shaped housing part and the cup nipple are enveloped by a plastic-extrusion coat on which a plug has been premolded to connect the magnetic coil to a mating plug. Due to the two labyrinths onto which the plastic is shrink-fitted, the magnetic coil is sealed from environmental influences, so that salt fog, which forms under certain environmental conditions, will not penetrate the transitions between the plastic of the plastic-extrusion coat and the metal of the sleeve-shaped housing part and travel along the metal walls to the magnetic coil to cause electrical damage there. Since the labyrinths are able to be produced only by machining, the production of these labyrinths is very expensive, which is reflected to a considerable extent in the production costs of the fuel injector.